The bones and connective tissue of an adult human spinal column comprises 26 discrete bones, which are anatomically categorized as being members of one of four distinct classifications: cervical, thoracic, lumbar and sacral. The spinal column consists of the bones coupled sequentially to one another by tri-joint complexes that consist of an anterior intervertebral disc and two posterior facet joints. The anterior intervertebral discs of adjacent bones are cushioning cartilage spacers.
The complexity of the spinal column renders it susceptible to several genetic, congenital or developmental irregularities or conditions. One of the most common includes scoliosis, which is a condition that involves complex lateral and rotational curvature and deformity in a human spine. Scoliosis impairs the body's skeletal support and complicates and compromises certain vital functions, such as breathing, circulation and nervous system lesions (subluxations). Additionally, pain is common in adulthood if left untreated. Major causes of scoliosis are idiopathic (i.e., unknown cause), congenital or inherited developmental anomalies, and neuromuscular disorders such as cerebral palsy or spinal muscular atrophy. Due to the health risks and discomfort associated with scoliosis, it is important to treat the afflicted patient in order to reduce or eliminate the condition. With time the scoliosis can become progressively worst.
Spinal surgeries to correct scoliosis are needed by a great many patients. The fact that the spine is a complex construction of bone, cartilage, arteries, veins and nerves surrounded by relatively strong deep intrinsic muscles that support and help move the spine makes spinal surgery difficult to perform and requires a high degree of skill on the part of the surgeon if successful results are to be obtained. Initially, all such spinal surgeries were carried out by what is referred to as “open” procedures wherein the spinal structures being operated upon were exposed via a relatively large skin incision that narrows down in conical fashion to the deep, bony operative target, cutting and destroying intervening soft tissue structures such as muscles, ligaments, arteries, veins and nerves. Formation of the large open incision involves severing and separating a large number of tendons, ligaments, and muscle fibers, and this tissue trauma has been found to cause the patient pain, prolonged hospital stays, prolonged recovery and permanent low back weakness. In addition, elongated spinal rods, sometimes referred to as Harrington rods, are often placed on a patient's spine to correct the scoliosis.
In view of the foregoing, it will be appreciated that there is a need for a method whereby a surgeon may carry out spinal surgery to correct scoliosis with minimal patient trauma. Furthermore, it is desirable that such techniques and apparatus be simple and reliable. Surgeons have been using the anterior lumbar spinal surgery approach for scoliosis since 1969. Advances in medical technology continue to increase the utility of anterior surgical approach in the lumbar spine for a variety of spinal disorders. This is especially true in light of the worldwide acceptance of minimal invasive surgery (MIS).